The success of wheat growing depended upon the ability quickly to harvest the crop. Wheat must be allowed to stand until it is fully ripened. Then it must be quickly reaped and stored away out of the reach of the rain and wet. For a few weeks in each year there was a great demand for labor on the wheat farms. And there was little labor to be had. Cyrus H. McCormick solved this problem for the wheat growers by inventing a horse reaper. The invention was made in 1831, but it was not until 1845 that the reaper came into general use. By 1855 the use of the horse reaper was adding every year fifty-five million dollars to the wealth of the country. Each year its use moved the fringe of civilization fifty miles farther west. Without harvesting machinery the rapid settlement of the West would have been impossible. And had not the West been rapidly settled by free whites, the whole history of the country between 1845 and 1865 would have been very different from what it has been. The influence of the horse reaper on our political history, therefore, is as important as the influence of the steam locomotive or of the cotton gin.
小麦种植的成功依赖于人们迅速收割小麦的能力。小麦在成熟之前不能倒伏，而且，在小麦成熟后要迅速收割并储藏起来，不能被雨淋湿。每年有好几周的时间麦场上都需要大量的劳动力，但能够找到的劳动力很少。塞勒斯oHo麦考密克通过发明马拉收割机为小麦种植者解决了这个问题。他于1831年发明收割机，但是直到1845年这种收割机才正式投入大规模的使用。到了1855年，马拉收割机每年可以为这个国家带来5500万美元的财富，每年它的使用都将文明向西推进50英里。如果没有收割机就不可能在西部迅速建立聚居地，如果西部没有白种自由民定居，1845~1865年美国的历史将完全改写。因此，马拉收割机与蒸汽机车或者轧棉机一样对美国政治历史产生了重要影响。